He said the Prophet (ﷺ) prayed for rain pointing the back of his hands to the sky. Muslim transmitted it.

وَعَنْ أَنَسٍ: أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ اسْتَسْقَى فَأَشَارَ بِظَهْرِ كَفَّيْهِ إِلَى السَّمَاءِ. رَوَاهُ مُسلم